The penultimate episode opens with a meeting between Haruno and Hachiman: she wants to "compare notes" about Yukino's future plans. This would be a perfect time for Hachiman to turn her own speech against herself: "Stand on your own two feet." That Haruno doesn't even know what her little sister plans to study in college speaks eloquently about the state of their relationship, and after all this time learning about her, there is no way anyone would believe she'd use that information for Yukino's good. Haruno is simply an antagonist at this point, with nothing positive to recommend for her - the closest to a villain Oregairu has to offer.
Unfortunately, Hachiman of course is not that brazen, so Haruno goes unreprimanded. Infuriatingly, she somehow knows about Hachiman's desire for genuine relationships, and weaves truth with lies in order to paralyze everything he's been working for - honest, real friendship. Yukino trusts Hachiman quite a bit, according to Haruno - but wait no, it's not trust, but something far more sinister. She's picked up that Yukino is in love with her friend, and claims "she hasn't changed a bit." But how on earth would Haruno know that? Yukino has changed, and we through Hachiman have seen her lower her walls and be vulnerable before others. The stoic, ice queen of perfection is no more. Haruno naturally can't see that, because Haruno refuses to enflesh it. "Is anything really genuine?" she muses. Of course, her answer is probably 'no,' and not without reason. It's not something you can calculate or deductively reason out; it's not something you can prove. True friendship, like true love, requires belief in another person, analogous to the faith a believer has in his God. Given the indefinite ways we can deceive ourselves or manipulate others or drive them away (Hachiman, Iroha, and Yukino, for example), you can never be sure either you or the other is being real. But for a true friend, as for a true lover or a true believer, that is almost irrelevant.
Part of the reason I hate Haruno so much is because she exercises such influence in this series, and because someone like that would attract me as well, if only on the superficial level. I like to think I'd cut all ties with her, but Hachiman can't resist the attentions of a smart, vivacious, intuitive, and extremely attractive girl, so he keeps talking to her - and I'd probably be no different, even though I know the flirty behavior is just a wall. Things and actions have meaning, and power, even if you know they're lies. Because she's older and furiously smart, she occupies a place of power with respect to the trio. And because all three of them are so new at this true friendship thing, they can't just shrug off her paralyzing interventions; because they've only just taken the first step, they're extremely vulnerable to exploitation, and exploitation defines Haruno.
Sensei, of course, is the precise opposite. She has never been this warm or encouraging with Hachiman before, and it's perfectly clear how proud she is of him, Yukino, and Yui. She really, really cares about them, and she's the only adult figure we've seen who does (Haruno, for obvious reasons, does not qualify). We've never seen her this gentle. Happy. Pleased. "People's perception of others gets clearer by the day. If you continue to spend time and grow with someone, you'll gradually understand them." And in response to his feeling that he and his friends haven't really grown, she hits the home run: "People don't usually look back to see how far they've come while they're still walking." She's seen their growth, recognizes it, and wants to make sure he knows she knows it. What she sees is real, and we know, because we have seen it too. With only one bizaare teacher as a guide, the three of them have discovered the joys of friendship. Parents or other authority figures have been no help, but Sensei has been there from the beginning, and guided the three of them with a steady hand. She is amazing.
As if to emphasize the contrast, Haruno appears, and in a sneering monologue, yet again combines truth with lies, and proves yet again that she holds a disproportionate amount of influence with the three. If they were wiser, Hachiman, Yukino, and Yui would have remembered Sensei and her warm, hopeful encouragement, and then they'd be able to dismiss and forget Haruno's deceiving speech. Sure, in a sense, the older sister is right: the three of them are not being straightforward, because the girls are in love with Hachiman, and Hachiman is in love with Yukino, even though he barely recognizes, much less accepts, that himself. Haruno prefers the old Yukino, who'd speak her mind without reservation. And? So what, Haruno? That old Yukino drove everyone around her away with her practice of cruelty by means of truth, and was naturally always alone. Is choosing not to vent your passions as you experience them necessarily disingenuous? I don't think so. Moreover, that old Yukino would have never dreamed about revealing her vulnerabilities before others, let alone reach out to them for help, whereas now she does both.
Haruno could be seen as trying to help these kids, but true help looks like Sensei: spend time with each other, and you will better understand one another. You don't need to be mocked belittled as fake and boring in order for that kind of growth to happen: the kind of friendship Sensei is pushing the three to have is self-correcting. Haruno's is self-centered, even Haruno-centered, because it would more fun for her to watch. The worst part about it all is how effective it is. It wrecks all of them. If it weren't clear before, what the three have been doing is clear to all of them now. They would have dealt with it themselves in due time, but Haruno pushed them too early, which made them paralyzed; unlike Hiratsuka-sensei, whose pushes were at the proper time, and lead to growth and good change. Now they're anxious and afraid, more ready to raise the walls again. Worse than harmful, Haruno's interventions are unnecessary in the extreme. She ought to be hated by all.
Enter the last person we want to see, Yukino's mother. "I want you to live freely and stay true to yourself, but I'm worried you'll go down the wrong path." Pretentious vomit. She wants to control her daughter and make her a replacement Haruno. In this vision, Yukino simply has to do what's expected of her. By choosing liberal arts, she's disappointed her family (presumably Haruno chose the sciences), so she's got some explaining to do.
So the final obstacles to friendship are enumerated: Yukino's awful family and a love triangle that somehow avoids most cliches - like the medieval stories where two knight-brothers both fall in love with the same girl. Sticking the landing will be hard.
